A film projector magnifies a 100 sq. cm. film strip on a screen. If the linear magnification is 4, the area of the magnified film on the screen is-
It is desired to photograph the image of an object placed at a distance of 3 m from a plane mirror the camera which is at a distance of 4.5 m from the mirror should be focussed for a distance of -
A photographer changes the aperture of his camera so that the new diameter of the aperture is twice the initial one, the ratio of new exposures time to the initial one is-
The exposure time of a camera lens at the f / 2.8 setting is (1/200) s. the correct time of exposure of f / 5.6 is -
An object 5 cm long and a pencil 10 cm long are placed in front of a pin hole camera such that their images have the same length. The ratio of the distance of the object from the pin hole to that of the pencil is-
The ‘f’ number of a camera lens is 4.5. Which of the following statement is correct-
The focal length of the objective of a microscope is-
When length of a microscope tube increases its magnifying power-
In a simple microscope, if the final image is located at infinity then its magnifying power-
In a simple two lens refracting microscope, the intermediate image, in normal use is-
The final image produced by a compound microscope is
In a simple microscope, if the final image is located at 25 cm from the eye placed close to the lens, then the magnifying power is
In astronomical telescope, the final image is formed at -
In which of the following the length of the tube is equal to the sum of the focal lengths of the field and eye lenses-
Two convex lenses of focal length 0.3 m and 0.05 m are used to make a telescope. The distance kept between them is equal to-
An astronomical telescope has a magnifying power 10. The focal length of the eye piece is 20 cm. the focal length of the objective is-
The magnifying power of an astronomical telescope can be increased, if we-
When the length of an astronomical telescope tube increases its magnifying power -
The resolving power of a telescope depends upon-
If an astronomical telescope has objective and eye-pieces of focal lengths 200 cm and 4 cm respectively, then the magnifying power of the telescope for the normal vision is
In question no. 22, the length of the telescope for normal vision, is
In question no.22, the magnifying power of the telescope for distinct vision is
In question no.22, the length of the telescope for distinct vision is
The objective of a small telescope has focal length 120 cm and diameter 5 cm. The focal length of the eye piece is 2 cm. The magnifying power of the telescope for distant object is -
With a simple microscope if the lens is held at a distance d from the eye and the image is formed at the least distance of distinct vision from the eye, then the magnifying power is
To remove the chromatic aberration, the combination of lenses should be such that
The distance between the objective lens and the eye lens of an astronomical telescope when adjusted for parallel light is 100 cm. The measured value of the magnification is 19. The focal lengths of the lenses are-
If we double the aperture of a photographic camera, the new exposure should be-
When the object is self- luminous, the resolving power of a microscope is given by the expression -
A Galilean telescope measures 9 cm from the objective to the eye- piece. The focal length of the objective is 15 cm. Its magnifying power is-
In order to increase the magnifying power of a telescope-
Statement I : The focal length of objective of telescope is larger than that of eye lens.
Statement II: Magnifying power of a telescope increases when the aperture’s diameter is reduced.
Statement I : The image formed by the simple microscope cannot be projected on the screen.
Statement II: The image formed by simple microscope is always virtual.
Statement I : In a simple microscope, image formed is virtual, erect and magnified.
Statement II: Object to be seen is held between optical centre and focus of a convex lens.
Statement I : Magnifying power of a compound microscope is negative.
Statement II: Final image is inverted with respect to the object.
Statement I : To increase the depth of focus, photographer decreases the aperture and increases the time of exposure.
Statement II: More light enters the camera when aperture is small.
The focal lengths of the objective and the eye-piece of a compound microscope are 1 cm and 5 cm respectively. An object is placed at a distance of 1.1 cm from the objective.
If the final image is formed at the least distance of distinct vision, the magnifying power is -
In previous questions, what is the distance between the two lenses ?
If the final image is formed at inifinity, the magnifying power and the distance between the lenses are respectively given by -
For the two given statements :
(1) The length of an astronomical telescope for normal vision is f0 + fe . (2) An astronomical telescope consisting of an objective of focal length 60 cm and a single eye lens of focal length 5 cm, is focussed on a distant object such that parallel rays emerge from the eye-lens. If the object subtends an angle of 2º at the objective, the angular width of the image is 24º.
An astronomical telescope has a large aperture to –
The image formed by an objective of a compound microscope is –